Hi, On Thu, Jul 16, 2020 at 04:32:09PM +0200, Ondřej Jirman wrote:
Hi Guido,
On Thu, Jul 16, 2020 at 04:08:43PM +0200, Guido Günther wrote:
Hi Ondrej, On Thu, Jul 16, 2020 at 02:37:51PM +0200, Ondrej Jirman wrote:
When extending the driver for xbd599 panel support I tried to do minimal changes and keep the existing initialization timing.
It turned out that it's not good enough and the existing init sequence is too aggressive and doesn't follow the specification. On PinePhone panel is being powered down/up during suspend/resume and with current timings this frequently leads to corrupted display.
Given the amount of ST7703 look alikes i don't think you can go by the datasheet and hope not to break other panels. The current sleeps cater for the rocktech panel (which suffered from similar issues you describe when we took other parameters) so you need to make those panel specific.
It should work on rocktech too. The patch mostly increases/reorders the delays slightly, to match the controller documentation. I don't see a reason to complicate the driver with per panel special delays, unless these patches don't work on your panel.
That's why i brought it up. It breaks the rocktech panel on blank/unblank loops where it just stays blank and then starts hitting DSI command timeouts. Cheers, -- Guido
The init sequence is still suboptimal, and doesn't follow the kernel docs completely, even after these patches. Controller spec also talks about adding some delay before enabling the backlight to avoid visual glitches.
Which is what enable callback is documented to be for. Currently part of the initialization that belongs to prepare callback is also done in enable callback.
I see the glitch (small vertical shift of the image on powerup), but personally don't care much to introduce even more delays to the driver, just for the cosmetic issue.
regards, o.
Cheers, -- Guido
This patch series fixes the problems.
The issue was reported by Samuel Holland.
Relevant screenshots from the datasheet:
Power on timing: https://megous.com/dl/tmp/35b72e674ce0ca27.png Power off timing: https://megous.com/dl/tmp/dea195517106ff17.png More optimal reset on poweron: https://megous.com/dl/tmp/a9e5caf14e1b0dc6.png Less optimal reset on poweron: https://megous.com/dl/tmp/246761039283c4cf.png Datasheet: https://megous.com/dl/tmp/ST7703_DS_v01_20160128.pdf
Please take a look.
thank you and regards, Ondrej Jirman
Ondrej Jirman (2): drm/panel: st7703: Make the sleep exit timing match the spec drm/panel: st7703: Fix the power up sequence of the panel
drivers/gpu/drm/panel/panel-sitronix-st7703.c | 29 ++++++++++--------- 1 file changed, 15 insertions(+), 14 deletions(-)
-- 2.27.0